Allocryptovalsa aceris T.Y. Du & Tibpromma, sp. nov.
Index Fungorum number: IF 558765; MycoBank number: MB 558765; Facesoffungi number: FoF 10261, Figs. 1, 2
Etymology – based on the host genus, Acer.
Saprobic on dead twigs of Acer palmatum Thunb. Sexual morph: Ascostromata gregarious, obviously, 3–11-ascomata, raised, immersed to semi-immersed, becoming erumpent through the host tissue, the surrounding host tissue obviously black. Ascomata (including neck) 500–660 µm high×230–380 µm diam. (x=558×310 μm, n=10), perithecial, gregarious, immersed in the stroma, obovoid to ellipsoid, coriaceous, dark brown to black, wrapped in white entostroma, ostiolate, papillate. Ostiolar canal 160–260 µm high × 95–200 µm diam. (x=224×172 μm, n=10), central, not protruding or protruding a little from the substrate, cylindrical, straight, dark brown to black, periphysate. Peridium 18–45 μm wide, composed of two type layers, outer layer comprised of several layers of thick-walled, dark brown to black cells of textura angularis, which are not fully fused with the host tissue; inner layer comprising 3–5 layers of thin-walled, hyaline cells of textura angularis. Hamathecium 2–4 μm wide, comprise few, granulate, filamentous, unbranched, septate, hyaline paraphyses, slightly constricted at the septa, tapering towards the apex. Asci (90–)100–145(–170) × (15–)16–24 µm (x = 116 × 18.6 μm, n = 10), spore-bearing part length (48–)55–100(− 121) μm (x = 75 μm, n = 20), polysporous, unitunicate, thin-walled, clavate, with long and fragile pedicellate, apically rounded, narrowing towards lower region. Ascospores 9–14×2–4 µm (x=12×2.8 μm, n=30), crowded, oblong to allantoid, pale yellowish at maturity, aseptate, slightly curved, smooth-walled, granules, without appendages and mucilaginous sheath. Asexual morph: Undetermined.
Culture characteristics – Colonies on PDA reaching 4 cm diam., after 4 days at room temperature (20–25 ℃), flattened, filamentous, filiform margin, with white aerial mycelia; reverse white, smooth, not produced pigments in culture, not sporulate in the culture.
Material examined – China, Yunnan Province, Kunming City, Kunming Botanical Garden, 25° 8′ 30″ N 102° 44′ 16″ E, live on dead twigs of Acer palmatum (Aceraceae), 19 March 2021, S. Tibpromma, KMD20, (HKAS 121126, holotype), ex-type culture, KUMCC 21-0085.
GenBank numbers – ITS: MZ727001, β-tubulin: OK043823
Notes – Our collection (HKAS 121126) clusters with Allocryptovalsa elaeidis (MFLUCC 15-0707) in the combined ITS and β-tubulin gene analysis (Fig. 3). The nucleotide comparison of ITS region of our collection with A. elaeidis gives two base pair difference, and the β-tubulin fragments of our collection is identical to A. elaeidis. However, morphological characters showed that our collection differs from A. elaeidis by 3–11-gregarious ascomata in black ascostromata, the surrounding host tissue, while A. elaeidis has 1–2-ascomata in ascostromata mostly solitary, surrounded by black circle on host surface (Figs. 1, 2) (Konta et al. 2020). Therefore, we introduce our collection as a novel species, Allocryptovalsa aceris and it is the first Allocryptovalsa species collected from Acer palmatum.
Figure 1 – Comparation of ascostromata on the host. a, b Allocryptovalsa elaeidis (MFLU 15-1438). c Allocryptovalsa aceris (HKAS 121126). Scale bars: a, c=500 µm, b=200 µm
Figure 2 – Allocryptovalsa aceris (HKAS 121126, holotype). a Appearance of ascostromata on the host. b Transverse sections through ascostroma. c, d Section through the ascostroma. e Ostiolate. f Ostiolate with periphysate. g, h Asci. i Paraphyses. j Peridium. k–m Ascospores. n Germinated ascospore. o, p Culture characteristic on PDA after 4 days (o=colony in front, p=colony in reverse). Scale bars: d=300 µm, e, f=100 µm, g–j=50 µm, k–m=10 µm, n=20 µm
Figure 3 – Phylogram generated from maximum likelihood analysis based on combined ITS and β-tubulin sequence data of 26 taxa, which comprised 1200 characters (ITS=471 bp, β-tubulin=729 bp). The best scoring RAxML tree with a final likelihood value of −5252.308511 is presented. The matrix had 432 distinct alignment patterns, with 39.91% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.232475, C=0.260249, G=0.230662, T=0.276614; substitution rates: AC=0.897989, AG=3.062620, AT=1.270241, CG=1.001517, CT=3.997945, GT=1.0; gamma distribution shape parameter α=0.713963. Bootstrap support for maximum likelihood (ML) equal to or greater than
50% and clade credibility values greater than 0.90 (the rounding of values to 2 decimal proportions) from Bayesian inference analysis are labelled at each node. Ex-type strains are in bold, while the new isolate is indicated in blue bold. The tree is rooted to Cryptovalsa ampelina (DRO101, A001)